Heating unit for fiber stretching installations



Julyl9, I968 HBOSCH ET AL 3,392,267

, 'HEATING UNIT FOR FIBER s'raa'rcumo INSTALLATIONS Filed June,l8, 1965 Y w 5 Sheets$heet l IN VEN TOR.

BY 3% 94m 9 H. BOSCH ET AL 3,392,267-

HEATING UNIT FOR FIBER STRETCHING INSTALLATIONS July 9, 19.68

3 Sheets-Sheet 2 Filed June 18, 1965 July 9, 1968 BOSCH ET HEATING UNIT FOR FIBER STRETCHING INSTALLATIONS 5 Sheets-Sheet 5 Filed June 18, 1965 h F 1 P! r M? 1 @EC C m W my i H L w; p p m Q a Q; a q a -m United States Patent ()1 lice 3,392,267 Patented July 9, 1968 3,392,267 HEATING UNIT FOR FIBER STRETCHING INSTALLATIONS Hugo Bosch, Offenbach am Main, and Werner Kegel,

Bergen-Enkheim, Germany, assignors, by mesne assignments, to Vickers-Zimmer Aktiengesellschaft, Planung and Ban von Indnstrieanlagen, Frankfurt am Main, Germany, a corporation of Germany Filed June 18, 1965, Ser. No. 470,664 Claims priority, application Germany, June 19, 1964,

10,915 (Filed under Rule 47(a) and 35 U.S.C. 116) 5 Claims. (Cl. 219399) ABSTRACT OF THE DISCLOSURE A synthetic fiber heating apparatus for continuous fiber stretching including an enclosure wherein a treatment chamber is defined between two vertically-spaced, rigid, heating boxes Which are supported to be freely movable to compensate for thermal stresses. A longitudinal horizontal aperture in one well of the enclosure provides access to the treatment chamber. Through a fixed feed line, heating fluid is provided for the heating boxes. Optionally, steam heating may be provided by a steam spray pipe arranged in the enclosure. Fibers move horizontally through the chamber.

A bafile plate is provided between the steam pipe and the fibers to direct steam above and below the fibers.

The invention relates to an apparatus for maintaining a controlled heating zone in which synthetic fibers may be stretched subsequent to polymerization and spinning.

In the production of synthetic fibers it is usually necessary to stretch filaments from the spinning nozzles to a high degree before further processing. It is necessary to heat the filaments during the stretching process, which is generally performed by two sets of stretching rollers driven at differing speeds. Heating is usually effected in heating chambers through which is passed the material to be stretched.

There are known in the art a number of different heating units for fiber stretching installations. Depending upon the properties of the material to be treated, most units are designed to permit dry heating and in addition, steaming of the material during the stretching process.

In such heating units, there is provided a double-walled heating body having on one side an aperture of circular or oval cross-section. Such aperture is used to introduce material to be stretched into the heating chamber. During operation, the aperture is closed. The hollow chamber of the heating unit is filled with a heating fluid, for example, with diphenyl, which is usually heated to the working temperature by an electrical resistance heating system. The temperature of the system depends on the requirements of the material to be stretched and may be, for example, in the range of 200 to 230 C. For steam-charging the treatment chamber, spray tubes are arranged above and below the material to be stretched.

Known heating units have the drawback that, during operation, considerable thermal stresses develop in the walls and supporting connections, which cause deformation and warping especially near the periphery of material-introducing aperture. Deformation and warping varies in degree over the length of the heating unit, which generally is several yards long. Due to the irregular dimensions of metal surrounding the apertures, severe deviations in aperture cross section also occur as the unit changes temperature. There also exists the problem of introducing into the heating unit material in the form of narrow, fiat thread cable composed of many minute threads, called capillaries, which are difficult to handle.

A further problem with respect to design of heating units involves the disposition of steam-forming apparatus. Such apparatus should be within the treatment chamber and be supported on the heating unit structure, which means such apparatus is subjected to the same thermal stresses as arise in the heating unit itself. Moreover, because of space limitations, such apparatus can be accommodated only above and below the thread cable or filaments to be stretched, in which arrangement there exists the danger that entrapped condensate droplets will strike against the thread cable, which may impair the quality of'resultant synthetic fibers. In particular, in subsequent dyeing of the material, color faults occur at places which contacted condensate droplets. Thus it is an object of this invention to provide a synthetic fiber heating apparatus to be used for controlling the temperature of synthetic materials while they are being stretched wherein the problems caused by thermal stresses of the heating equipment are: eliminated.

It is another object of this invention to provide such heating apparatus wherein associated steam-producing apparatus is built integral with the heating apparatus to eliminate problems caused by thermal stresses.

Another object of this invention is to provide a synthetic fiber heating apparatus including means for producing steam wherein there is eliminated any contacting of-steam condensation droplets with fiber material.

Other objects of the invention will become apparent as it is hereinafter more fully described.

The improved heating unit of the invention comprises a treatment chamber which is formed between two rigid heating boxes spaced one above the other, supported as hereinafter described to be freely movable to avoid thermal stresses. Preferably the lower and upper heating boxes are supported on a set of lower and upper brackets. The upper box has secured to its supports or clamping means consisting of bars which are welded to the upper heating box which bars are supported loosely by the upper brackets. The two heating boxes are connected to a fixed feed line through which is fed heating fluid. The connection piece of the fixed feed line is the reference point from which the boxes move by thermal expansion and contraction.

For providing steam to the boxes there is arranged, preferably at the horizontal level of the fibrous material on the side away from the aperture, a steam spray pipe. Between the steam pipe and the fibrous material is a bafile plate. The steam pipe and the baffle plate are fastened, preferably to a wall plate which is external of the boxes andwhich shields the treatment chamber from outside influences. The wall plate may be attached to the same brackets which serve to support the two heating boxes, so that the steam pipe is not directly connected to and is independent of the heating boxes.

The aperture in the treatment chamber is formed between the longitudinal edges of the wall plate and can be closed by shutters. Deformation of the aperture is virtually precluded because of the freely movable suspension of the heating boxes.

The baffle plate which is arranged between the steam pipe and the fibrous material provides for uniform steam conduction above and below the material transversely of its moving direction and at the same time prevents contact of condensate droplets with the fibrous material. Keeping the material free .of condensate droplets is further aided by the fact that the surfaces of the heating boxes bounding the treatment chamber are somewhat inclined with respect to the horizontal, so that condensate forming in 3 the heating boxes flows to the side edge and does not strike the thread cable.

The invention will be best understood with aid of the drawings wherein:

FIG. 1 illustrates in cross section a heating unit according to the invention;

FIG. 2 illustrates a longitudinal section along line 11-11 of FIG. 1; and

FIG. 3 illustrates in cross section a view along line III-III of FIG. 2.

In the heating unit for fiber stretching installations as represented in the drawings, there are arranged, spaced one above the other, two long flat heating boxes 1 and 2 of rectangular plan and approximately rectangular crosssection, between which there is formed a treatment chamber 3 in which fibrous material 4 is stretched. The length of heating boxes 1 and 2 and thereby the length of treatment chamber 3 is about 3 to 8 meters. Fibrous material 4 is a thread cable and has the form of a flat band which consists of many individual capillaries, the number of which, depends on the layout of the installation, and may be several ten thousands .or hundred thousands or even several millions. The material moves longitudinally along the center of treatment chamber 3 and, in a typical process, it may be under tension of several tons.

Heating boxes 1 and 2, as best seen in FIGS. 2 and 3, are hollow bodies closed on all sides and reinforced by a plurality of perforated struts 5. Boxes 1 and 2 in operation are filled with heating fluid, for example, diphenyl. In the space within boxes 1 and 2 between the struts 5 there extend pipes 6 which may be provided externally with fins 7. In pipes 6 are inserted heating elements (not shown), preferably electrical resistance heaters, by which the heating fluid is brought to the working temperature, for example, to 200 to 230 C., depending on the temperature desired in treatment chamber 3. Pipes 6 are secured to heating boxes 1 and 2 by means of end pieces 8 which are welded into the heating boxes and which are internally threaded for use to support boxes 1 and 2.

As shown in FIG. 1, heating boxes 1 and 2 are supported by brackets 10 and 10' and 11 and 11', respectively, which, in turn, are secured rigidly to frame 9 indicated diagrammatically in FIG. 1 by several angle irons. Lower heating box 2 is mounted freely on lower brackets 11 and 11, while upper heating box 1 is freely suspended by means of supports 12 on lower brackets 10 and 10. Supports .or clamping devices 12 may have the form of profile bars, which are fastened at their centers to heating box 1 with their ends supported by brackets 10 and 10' as shown in FIG. 1.

At one end of heating boxes 1 and 2 there is flanged connecting pieces 13 and 14, respectively, to a common connecting piece 15. Connecting piece 15 serves as a manifold for directing heating fluid to heating boxes 1 and 2 from source tank 16 which may be suspended above upper brackets 10 and 10' on frame 9. Tank 16 is partially filled with heating fluid and serves as a vapor chamber for the heating fluid as well as a source of liquid. On tank 16 there is connected draw-off outlet 17 for removal of vaporized heating fluid. Tank 16 is also provided with an inlet (not shown) through which heating fluid is fed into the tank. To empty the entire fluid system, the lower end of manifold 15 is provided with discharge connection 18.

From the preceding description it can be seen that heating boxes 1 and 2 are fixedly secured to the heating unit only at a single point, namely at connecting pieces 13 and 14. Boxes 1 and 2 are otherwise free to move on brackets 10 and 10' and 11 and 11, respectively, thereby eliminating thermal stresses which may warp or distort the shape of the boxes and treatment chamber 3. Moreover, the resultant structure provides a simple assemblage since heating boxes 1 and 2 need only be pushed onto their brackets from the side until connecting pieces 13 and 14 are aligned with manifold 15.

In order to be able to steam as well as heat fibrous materials in treatment chamber 3, there is provided steam pipe 20 at the horizontal level of the fibrous material. Pipe 20 extends over the length of treatment chamber 3 on the same side of the chamber as pieces 13 and 14. Pipe 20 is supplied with steam through inlet pipe 21. Pipe 20 carries at its terminus a number of spray nozzles 22, through which steam is fed to treatment chamber 3. Between steam pipe 20 and fibrous material 4 there is located bafile 23 which divides the steam flow into two portions, one above and one below the treated material. The steam flow is transverse to the longitudinally extending fibrous material. By provision of split steam flow transverse to the material to be treated, uniform steaming is achieved and contact of condensate drops with fibrous material is prevented.

To effect a vapor-tight seal of treatment space 3 there is provided wall plate 30 which extends around heating boxes 1 and 2 and is attached to frame 9. At the horizontal level of treatment chamber 3 on the side opposite steam pipe 20 there is left open in plate 30 an aperture 27 which forms the operating Opening for the entry of the fibrous material to be treated. Such opening extends over the entire length of treatment chamber 3 and may be closed by one or more shutters 28.

On the side of wall plate 30 .opposite aperture 27 there is provided a plurality of packed openings (not shown) for lead-through of connecting pieces 13 and 14 as well as for introduction of heating elements (not shown) into pipes 6. Moreover, plate 30 has on its rear longitudinal side located in treatment chamber 3 several holding straps 24 to which are attached steam pipe 20 and baffle plate 23. In this manner heating boxes 1 and 2 are secured independent of pipe 20 and baffle plate 23 and will not interfere with the movement of one another caused by thermal stresses.

The bottom surface of wall plate 30 is formed into a collecting funnel 31 for directing the flow of accumulated condensate which flows through funnel 31 to drain pipe 32. For the discharge of steam there is provided above upper heating box 1 several discharge outlets through wall plate 30 (not shown) which lead into outlet pipe 33.

The surfaces of boxes 1 and 2 facing treatment chamber 3 are preferably inclined to the horizontal in a direction transverse to the fibrous material so that the distance between heating boxes 1 and 2 is slightly greater in the zone of the operating aperture 27 than in the zone of steam pipe 20, as is shown in FIG. 1. This inclination of the inner boundary surfaces of the heating boxes aids in steam conduction in treatment chamber 3 and insures particularly, that any condensate formed on such surfaces flows off to the side edges and does not drip on the fibrous material.

To start the unit, fibrous material to be treated is inserted into chamber 3 through aperture 27 with shutter 28 open. During such insertion, supporting straps (not shown) running transversely across the chamber slightly above box 2 prevent direct contact of the material with heating box 2. Such supporting straps are also useful to support material during temporary shut-down of the unit. The insertion process can be carried out without difficulties, even with the unit at operating temperature, since aperture 27 is not at all distorted or deformed by thermal stresses of the equipment. This is especially important in view of the fact that the space between heating boxes 1 and 2 and therefore the size of aperture 27 is relatively small.

On the entry and exit end faces of the heating unit there may be provided vertically adjustable slides (not shown) by which the size of the slot opening through which the fibrous material extends can be maintained at a minimum, thereby minimizing heat losses from the ends of the heating unit. Moreover, to further reduce heat losses the zone between wall plate 30 and outer casing 40 (indicated schematically) may be provided with insulation. Likewise shutters 28 may be insulated.

We have disclosed one embodiment of our invention, and those skilled in the art will recognize that various modifications can be made within the scope of the invention which is limited solely by the appended claims.

We claim:

1. An apparatus for heating during stretching synthetic fibers moving continuously along a longitudinal axial path comprising:

(a) means defining an enclosure including spaced apart and opposed first and second vertical walls disposed parallel to the longitudinal axial path of said fibers,

(b) means defining a plurality of box-like heaters disposed in said enclosure,

said heaters having extended, generally horizontally oriented opposed and spaced apart heating surfaces which define a heating chamber therebetween through which said fibers travel,

said first wall being fixed,

said second wall having a longitudinal aperture therein to provide lateral access to said chamher for introduction of said fibers, and includmg:

(i) means operable to open and close said longitudinal aperture,

() means for supporting said heater means in said enclosure independent of said first and second walls, said heater means being free to move in response to thermal stresses,

(d) means for introducing heating fluid into the interior of said heater means through said first wall,

said introducing means being independent of distortions of said first wall produced in response to thermal stresses, whereby deviations in aperture cross section caused by thermal deformation and warping are obviated and fiber insertion at operating temperatures is permitted.

2.. An apparatus as in claim 1 which includes:

(a) means for electrically heating said heating fluid disposed in said box-like heater means,

said means being controllable to maintain said fluid at predetermined temperatures.

3. An apparatus as in claim 1 which includes:

(a) means for providing steam to said chamber comprising:

(i) a pipe extending parallel to the path of said fibers and disposed substantially in the horizontal plane of said fibers,

said pipe having a plurality of spray openings therein, and (b) means defining a bafiie plate disposed adjacent to said pipe for directing steam from said nozzles to upper and lower portions of said chamber whereby said fibers are substantially free from direct impingement of said steam thereupon,

said pipe and baffle plate means being supported by said first Wall of said enclosure thereby being free to move in response to thermal stresses independently of said heater means.

4. Apparatus of claim 3 wherein said heating surfaces of said heating means are inclined from the horizontal to diverge in the direction of said aperture in said second wall.

5. Apparatus for heating synthetic fibers during stretching comprising an enclosure having a lateral aperture for entry of fibrous material, a plurality of box-like heaters in said enclosure having extended opposed heated surfaces which define a chamber and means operable to open and close the aperture of said enclosure to provide lateral access to said chamber, said box-like heaters having means for providing heating fluid thereto and being supported in said enclosure to provide for free movement in response to thermal stresses, means for providing steam to said chamber, said means including a longitudinally extending pipe having a plurality of spray nozzles and a baffie plate adjacent to said pipe for directing steam from said nozzles to upper and lower portions of said chamber, said steam pipe and bafiie plate being supported by walls of said enclosure and move in response to thermal stresses independently of said box-like heaters.

References Cited UNITED STATES PATENTS 629,158 7/1889 Gage 34151 X 2,520,202 8/1950 Frearson et al 2859.5 2,590,849 4/1952 Dungler 34--23 2,674,809 4/1954 Meienhofer 219388 X FOREIGN PATENTS 1,028,103 2/1953 France.

RICHARD M. WOOD, Primary Examiner. C. L. ALBRITTON, Assistant Examiner. 

